Coupler devices are used on earth moving equipment for the removal and attachment of equipment such as buckets and rock breakers. The coupling device is commonly referred to as a ‘quick coupler’ or ‘quick hitch’. These devices depend on positive hydraulic pressure and/or mechanical locks to hold buckets and other attachments in place. The use of quick coupler mechanisms on excavators and other earth moving equipment is common practice, as they allow operators to easily change buckets or attachments.
Where an excavator fitted with a Quick Coupler device is being operated, drivers should ensure the following before operating the machine:                1. The correct procedure for securing the attachment (bucket/rock breaker etc.) is employed and that the locking mechanism is fully deployed and secured.        2. Once the attachment is secured before use, and when all persons in the vicinity are sufficiently clear of the machine, the driver should aggressively shake the dipper arm to ensure that the attachment cannot come loose.        
In some designs of quick couplers the point of contact between the pins and the locking member can be quite small. This feature, coupled with high concentrated loads, can lead to the problem that these bucket pins can wear and quickly loosen. Some couplers that have being designed for use with one particular make of excavator, with buckets and other tools then being designed for use with these excavators. This means that such couplers often cannot be used to pick up a bucket or attachments of another manufacturer. This can be a substantial disadvantage, especially on sites where there may be excavators from several different manufacturers all being operated by the same contractor. Some couplers have gravity operated release mechanisms that rely on the machine hydraulic oil that is supplied for the excavator for operation. However, in some cases the oil can have dirt or debits within the oil, which in turn may prevent the mechanism from operating. Another problem with existing couplers is that due to the loss of hydraulic pressure which may occur due to damage to the hydraulic cylinders, an attachment may be prevented from being removed.
Accordingly it is an object of the present invention to provide an improved coupler device to overcome at least one of the above mentioned problems.